Friday, December 14, 2018

Big improvements for the snow outlook next week with some substantial snow amounts possible for high country Mon/Tue

Thanks to the combination of northwest flow at jet stream level and the refrigerating effect of the existing deep December snowpack, cold air continues to dominate interior New England in unique fashion. Unique because the region is about the only place in the United States which is experiencing winter conditions as the cold has been largely scoured away from much of the rest of the nation. It's been a long time since I remember a weather pattern that has left us this distinguished. I certainly recall a few years in the early 90's where New England was the coldest relative to average for the winter season and one season in particular, 1991-92 which especially stands out because of how dramatic it was and because it was also a El Nino winter, much like this one and of a similar intensity.

I am delighted to report that the outlook going forward continues to improve. There are no particular indications of any big storms and the weather pattern continues to look non-arctic both for Vermont and for much of the lower half of North America. That said, the outlook on temperatures continues to move in the "not as mild" direction and what's better is the introduction of some accumulating snowfall to the outlook for at least early next week and quite possibly later in the week as well.

All of that talk about the tightened jet stream in the Pacific will finally bring some milder temperatures to Vermont, but we aren't expecting much if any rain. Temperatures will sneak above the freezing mark by evening on Friday and stay there for a good part of Saturday but will will remain below the 40-degree mark. In addition, much of the rain will stay to the south of Vermont and winds will remain calm. This basically means very little damage to the existing snow and clearing skies Saturday night will allow temperatures to chill back down to well-below freezing levels. Some early sun will send readings back toward the freezing mark Sunday before clouds encompass the region in advance of our next interesting little weather system.

It would be wrong to call it a Alberta Clipper since it won't enter the nation via that route. For now, lets just refer to it as the "Provincial Plunger" since the impulse originates from a vigorous Canadian storm system that will travel across central Canada over the weekend. This particular weather feature will grab the polar jet and yank it southward toward northern New England. Though the storm isn't flush with moisture, it has a little bit and will also bring the combination of instability and a very favorable wind direction for the north central Green's. Snowfall across the high country will begin early Monday and persist through much of the day into Monday night and even Tuesday. Accumulations will be elevations sensitive and the snow will be squally in nature but could be substantial. It would be very early to promise a foot-plus but that is within the range of possibilities. For now, I think 6 inches over that two day span (Monday-Tuesday) is a conservative guess and this is with modest temperatures mostly in the twenties. Though the rest of the week looks mild over the rest of the United States and not especially cold in New England, readings will generally remain below the freezing mark and the late week period brings the possibility for more snowfall or at worst some mixed precipitation (if everything goes wrong and that is not the trend). This second system is more of a traditional clipper-like storm which may or may not travel far enough south to deliver more snowfall but I have to admit, the outlook looks vastly improved.

Moving forward into the days immediately prior-to and during the X-Mas holiday, we are still contending with some adverse drivers in the weather pattern. The Arctic Oscillation is expected to be more negative now verses expectations from a few days ago and this will counter the negative influences from the MJO-EPO. But those influences will remain somewhat in play going into the holiday at a slightly weaker level. Can we again produce a little more late-2018 magic ? Quite possible again, but it would be disingenuous of me to suggest that we are obstacle-free in the Dec 21-26 range.

1 comment:

Anonymous said...

Fingers crossed for some more snow. I can't remember a start to ski season like this for several years. The conditions have been excellent. Now if we could just get some nice long stretches of ice making temps! :D